1. Field of the Invention
The present invention relates to a method for manufacturing an inkjet recording medium which has an ink receiving layer for receiving ink.
2. Description of the Related Art
In regard to inkjet recording methods, inkjet recording media in which the recording layer for receiving ink is constituted of a porous structure for the purpose of improving general properties, have been proposed and put into practical use. For example, there is available an inkjet recording medium in which a recording layer containing inorganic pigment particles and a water-soluble binder, and having high porosity has been provided on a support. Since such an inkjet recording medium has a porous structure, the inkjet recording medium has excellent ink receptivity (quick dryability) and high glossiness, and thus is widely used as a material capable of recording photograph-like images.
A recording layer having high porosity, which is formed by using inorganic pigment particles and a water-soluble binder, generally has particles of small size and a high content of particles. Therefore, after applying a coating liquid to form a film, cracks may be generated in the formed film during drying the film. These cracks are prone to occur, particularly in the case of, for example, drying at a relatively high temperature so as to shorten the drying time, and the cracks are likely to occur during drying after the coating, specifically during the period of transition from constant-rate drying to decreasing-rate drying.
As a method of preventing cracks, a method of increasing the viscosity of the binder in the coating liquid has been known. However, viscosity increase is not desirable from the viewpoint of, for example, unevenness in the coating. In another method, cracks that occur during drying after coating can be prevented by using a binder such as acetoacetyl-modified polyvinyl alcohol in combination with a crosslinking agent.
Meanwhile, from the viewpoint of recording photograph-like images, it is important that bleeding of ink (i.e., the image) does not occur after recording, and as a method of preventing the bleeding of ink, there are known methods of incorporating a cationic polymer, a polyvalent metal compound or the like into the recording layer on which the ink is to be deposited, or of using water-soluble cellulose derivatives.
In relation to the cracks or ink bleeding described above, a recording material for inkjet printing provided with an ink receiving layer which includes a two-layered coating layer formed by simultaneously applying an ink receiving layer which contains a resin binder having a keto group, and an ink receiving layer which contains a crosslinking agent, to be adjacent to each other (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2005-199671), or an inkjet recording sheet formed by sequentially laminating an undercoat layer containing a binding agent, a crosslinking agent and a water-soluble cellulose derivative as main components, and an ink-accepting layer containing inorganic fine particles and an acetoacetyl-modified polyvinyl alcohol as main components (see, for example, JP-A No. 2005-271441), have been disclosed. It is suggested that the former is free from cracks and has excellent water resistance, while the latter has high film strength.
There is also disclosed a method for manufacturing an inkjet recording medium, the method including applying a colorant receiving layer coating liquid containing a dispersion of inorganic fine particles dispersed in an aqueous medium containing a film-hardening agent and a dispersant. The colorant receiving layer coating liquid also contains hydroxypropyl cellulose and/or a cationic urethane resin (see, for example, JP-A No. 2004-358774). It is suggested that, according to this method, favorable dispersibility of the inorganic fine particles is achieved, and bleeding with a lapse of time does not occur.
Furthermore, a recording method of using an inkjet recording medium has also been disclosed (see, for example, JP-A No. 2007-196396). The inkjet recording medium is produced by incorporating a water-soluble metal salt into an ink receiving layer in order to enhance the ozone resistance of images in the case where a dye, particularly a phthalocyanine-based dye, is used as a colorant.